Topology errors of power network can affect the accuracy and may even lead to non-convergence of state estimation. This paper proposes a transfer power flow method for topology error identification. Using this method， by comparing the current telemetry data with the result of the base state estimation， the transfer power flow can be obtained. The paper also introduces a method to tackle cases of single line topology error and multiple bad measurements by analyzing the relationship between transfer power flow and the change of topology， as well as the effect of bad data， so as to improve the accuracy of state estimation. Its performances are highlighted via simulations performed on a real power network.